Blade fastening



Patented Oct. 16, 1928.

UNIT ED STATES i 1,681,891' PATENT OFFICE.

JAMES L. RAY, OF ESSI'NGTON, PENNSYLVANIA, ASSIGNOR. TO WESTINGrI-IOUSEy ELEC-- TRIC & MANUFACTURING COMPANY,

A CORPORATION OF PENNSYLVANIA.

BLADE FASTENING.

Application filedy September ture, and which. wheny assembled shall provide` a sturdy unitary structure.

Thespecifle object of my invention is to;

provide, in a lturbine havingl a rotorfwi-th undercut grooves for the mounting of blades therein and a widened portion in the groove Cil for the insertion of blades, means for securin g a bla de mountedl in the widened portion of the groove. y

'Apparatus embodying features, of my invention is illustrated in the accompanying drawings forming a part of this specification in which Fig. 1 is a perspective view showing a fragment of a turbine rotor having anH undercut groove with blades; mounted therein and having a widenedportion'for the insertion of said blades; Fig. 2V is a plan, view orl a turbine blade mounted 'in the widened por-A tion of the undercut groove and secured in accordance with myinvention; Fig. 3 is a sectional view `taken on the line III-III of Fig. 2; and Fig. 4 isan exploded view-in perspective of my improved blade fastening means. In the construction of elasticr fluid turbines,

yit has been found desirable in order to secure the moving blades in position, especially where the blades are subjected to high velocities and consequent heavy centrifugal stress, to provide Vtherotor with some form of undercut groove and to. provide blades having root portions fitting the undercut groove in the rotor in order to have a more sturdy, unitary structure. TWherever turbine blades are mounted in this way, it is necessary to provide the undercutl groove with a widened portion in order that-the bladev roots may he inserted in the groove, from which widened portion the blades are moved around the rotor to their ultimate positions. Difficulties haveheretofore been encountered in providing means for holding a blade mountedinfthe widened portion because of the high centrifugalstress to. which the lblade is subjected and because of the difliculty of providing adequate lfastening means at the side of the blade root. lIn accordance with my invention, I form the widened portion of the undercut lgroove' with serrated sides and provide a locking piece at each. side of the blade root and fitting 8, 1924. Serial No.v736,652. Y

I drilla tapered hole common to the lockingI piece, the filling piece and the wedges at each side of the blade and screw ay tapered plug into the hole, firmly locking the assembled structure togetheiz v Referring now to the drawings for a more detailed description ofmy invention I show in Fig. 1 at l() a fragment of a turbine rotor provided with an .undercut groove 11, having blades 12 mounted therein. The blades 12 are provided with root portions. 13, fitting the sides of the groove 11. In order. that the kblades 12 may be inserted in the groove 11 I providey the groove with a widened portion 14- through which the blades are inserted and `moved around the rotor to. their ultimate.

' fitting diagonally across the groove. 11. I

accordingly show one side of the` widened portion 14 as being offset from .the other in order that the holding.' means 'for the blade to be mounted therein may have a better bear` ing on the `blade root. Where blades are em- 'ployed having a root portion extending straight across the groove,l 11 it is to be understood that the widened portion 14 should be formed accordingly.

In order to secure a blade in the' widened portion 14 after the groove 11 has been completely filled', except for the widenedportion,

I' provide the widenedportion 14: with ser-rations 16 which cooperate with similar'serrations of a filling piece 17 and a locking piece 18 inserted at each 'side of the blade for holding said blade in position. The locking piece 18, at one side, is provided with a proiection lun 19 complemental contour to the blade root Y 13 and is-provided with serrations 21 cooperating with the serrations 16 of the widened portion 14. vThe filling piece 17 and locking` piece y18 are ofsuch thickness thatk when placed'in the widened portion 14 and moved as far to the side as possible, theypermit the insertion of' the blade root 13 into the widened portion 1L1. After insertion of the last blade root 13 the locking pieces 18, one at each side of the blade, are moved over toward the blade so that the projection 19 engages with the blade root 13. I then drive compound wedges 22 and 23 between the filling pieces 17 and the filling piece 17, compound wedges 22 and 23 and the locking pieee 18, firmly locking them in position and at the saine time providing further wedge means, whereby al more sturdy unitary structure is obtained. `After' assembly the top of the tapered plug may be cut off smooth as shown in Fig. 2 and at the left in Fig. 3. 1

The outward stresses of each locking piece 18, caused by the centrifugal force of the blade or blades 12 with which it interlocks,

are transmitted to the rotor 1t) in two ways.

A portion of the stresses is transmitted directly to the circumferentially opposite sides of the widened portion 11i by the sorrations 16 and 21 and another portion is transmitted through the tapered plug 26 and filling piece 17 to the outer end of widened portion 14e.

From the foregoing it will be appa-rent that I have invented an improved blade fastening for securing a turbineblade in the widened portion of an undercut groove, simple of design, easy7 of assembly and dis-assembly and which provides a sturdy unitary structure.

While I have shown my invention in but i one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications, without departing from the spirit thereof, and I desire, therefore that only suoli limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is: Y

1. In a turbine, the combination of a rotor provided with an undercut groove, said groove having a widenedv portionfor the'insertion of blades in the groove, blades mounted in the groove, a blade mounted in the widened portion and having a. root portion complemental to the undercut groove, a locking piece fitting the root portion of the blade, a filling piece fitting the widened portion of the groove, and wedge means between the locking piece and the filling piece for holding the locking piece, the `lill pieee and the blade in position.

2. In a turbine, the combination of a rotor having an undercut groove provided with a widened portion for the insertion of blades in the groove, a blade mounted in the widened portion and having a root portion compleinental to the undercut groove, locking pieces at cach side of the blade and fitting the root portion thereof, filling pieces at each side of the widened portion of the groove, and wedge means between the locking pieces and the filling pieces. y

3. In a turbine, the combination of a rotor having an undercut groove provided with al widened portion for the insertion of blades yin the groove, a blade mount-ed in the widened portion. and having a root portion coinpleniental to the undercut groove, vlocking pieces 'at each side of the blade and fitting the root portion thereof, filling pieces at each side of the widened portion of the groove, wedges between the locking pieces and the filling pieces, and means for locking the locking pieces, the 'filling pieces, and the wedges in position. l 'Y 4. In a turbine, the combination of'a rotor' having an undercut groove provided with aV widened portion for the insertion of blades in the groove, said widened portion having serrated sides, a looking piece at the side ofthe blade fitting the root portion of the blade and having serrations fittingthe serrations of the widened portion, a filling piece at the outer side of the widened portion and having serrations fitting the serrations of the widened portion, lwedges between the locking piece and the filling piece, and a single member engaging and locking the locking piece, the filling piece, and the wedges in position.`

5. In a turbine, the combination of a rotor 'having an undercut groove provided with a widened portion for the insertion of blades inV the groove, said widened portion having serrated sides, a blade mounted in the widened portion, a locking piece at the side Vof the blade fitting the root portion of the blade and vhaving serrations fitting the serrations of the widened portion, a filling piece at the outer side of the 'widened portion and having serrations fitting the serrationsof the widened portion, wedges between the locking piece and the filling piece, and means for looking the locking piece, the filling piece'and wedges in position comprising aftapered threaded vplugengaging with said filling piece, the

wedges and the locking piece. p Y Y 6. In a turbine, lthe combination of a rotor having an undercut groove provided with a Vwidened portion for the insertion of blades in the groove, said widened portion having ser'- rated sides,- 'a blade mounted in the 'widened portion and having a root portion complemental to the undercut groove, a packing piece at eaoh side of the blade, fitting the root portion of the blade, and having serrations fitting the sei-rations of the widened portion, a filling piece at each outer side of the widened portion and having serrations fitting the lll) serrations of the widened portion, wedges between each of the locking pieces and its associated illing piece, and means at each side of the blade for locking the locking piece, the filling piece and wedges in position comprising a tapered threaded plug engaging with the filling piece, the wedges and the locking piece. e f

7 In a turbine, the combination of a rotor having an undercut groove provided With a widened portion for the insertion of blades Y in the groove, a blade mounted in the widened portion, a locking piece at theside of the blade and having interlocking en agement therewith, a filling piece at the si e of the widened portion, Wedging means between the locking piece and the filling piece, and means for transmitting radial stresses from the blade through the locking piece, Wedge means and filling piece to the rotor.

In testimony whereof, I have hereunto subscribed my name this second day of September, 1924.

' v JAMES L. RAY. 

